The present invention provides a target unit and a sublimation apparatus suitable for use in a method for producing Cu67 radioisotope suitable for use in medical applications. The apparatus comprises a sublimation tube with one open end. The sublimation tube contains an ingot comprising Zn68 and Cu67 in a ceramic capsule contacting a closed end the sublimation tube. A removable vacuum dome is sealable over the open end of the sublimation tube so that interior of the apparatus can be placed under vacuum.